99 tahoe torque converter/overdrive in&out

[RGriffith]

i have a 99 tahoe 2 door sport edition. when going down the road around 45-60 mph it goes in and out of overdrive. Like the torque converter is not locking in. anyone else have this problem? if so please let me know the solutions!! thanks

 

[SunlitComet]

it is a common issue to have the brake light switch do that when it stats to fail. but perhaps you can get scanned for codes that do not actively light up the CEL for more clues.

 

[RGriffith]

now is that the white box that is under the dash attached to the brake petal?

 

[SunlitComet]

yes. it s under $15 if you just want to throw a cheap part at it first. beyond that it is a tranny or pcm issue.